The exterior surfaces of buildings are usually sealed against water penetration. Often, a waterproofing composition is applied to these surfaces to prevent water ingress. The composition may be applied with a trowel or laid by placing preformed sheets of the composition onto a surface. These waterproofing materials may be used on virtually any structural surface, including both vertical and horizontal surfaces. For example, one common application is in waterproofing roofs.
Besides enduring the onslaught of wind, rain, and sun, these coatings must resist degradation due to the day-to-night temperature cycles and the more severe winter-to-summer temperature cycles. In particular, exposed waterproofing materials must remain flexible when the temperature changes as any cracking of the coating may permit the subsequent ingress of water. Of course, water leakage often leads to damage to the structure of the building and possibly to the building's contents.
As is known in the art, some waterproofing compositions contain mixtures of asphalt, rubber, and filler material. In these compositions, the rubber is usually added to enhance elasticity of the asphalt/rubber mixture. The asphalt is used generally to bind particles of the filler material together and to provide weather resistance to the coating. The filler material is added generally to reduce the cost of the sealant composition but may be added to enhance certain properties of the coating formed of the sealant composition. However, the amount of the filler material that can be added to compositions containing only asphalt/rubber is limited. For example, presently available asphalt/rubber compositions may contain about 16 wt. % of a filler material such as calcium carbonate.
The cost of waterproofing compositions has risen sharply in the last few years due, in part, to an increase in the cost of petroleum—the source of most commercial asphalt. While the cost of waterproofing compositions has increased, builders, to maintain their competitiveness, have demanded lower cost building products in an effort to keep their material costs within affordable levels. Accordingly, waterproofing or sealant manufacturers are under pressure to provide cost effective waterproofing materials while fulfilling the builders' demand for products that are easy to use, that do not crack at low temperatures, and that are affordable. Although adding additional filler material to existing asphalt/rubber only compositions may reduce their cost, adding more filler material to these compositions creates other problems. For example, the composition becomes more difficult to manufacture, and, similarly, adding filler material to these compositions renders them difficult or impossible to effectively apply.
A need therefore exists for affordable waterproofing and sealant compositions that are capable of being highly filled yet have equivalent or improved lower temperature flexibility.